In the formation of compost, it is customary to arrange waste material, such as sludge from sewage treatment plants or partly decayed vegetation, in well defined windrows on a large field and to mechanically treat the waste material in each windrow by moving a straddle type machine along the windrow with the wheels of the machine rolling on solid ground on opposite sides of the windrow. A tunnel frame of the machine having its tunnel axis parallel to the windrow axis carries beating, chopping or other agitating means to churn and turn over the waste material while the machine traverses each windrow. A typical prior art machine of this character is shown in U.S. Pat. No. 4,019,723.
In accordance with this invention, a new and more efficient waste material treatment method and apparatus are provided, and up to four times as much material can be treated in accordance with the invention in a given space in comparison to the prior art with an obvious great economic advantage. The necessity for windrowing the material prior to its mechanical treatment is entirely eliminated.
By the present method, continuous deep layers of waste material, up to six or eight feet in depth extending over wide areas, are treated in a continuing process without disturbing the continuity of the material mass or layer.
The machine employed to practice the method includes a tunnel frame carrying within it the appropriate waste material mechanical working or treatment elements and the tunnel frame is set at an oblique angle to the pathway which the machine carves or forms for itself through the deep material layer in a number of forward and reverse passes. The wheels of the machine which establish the direction of the pathway are held at acute angles to the tunnel axis of the machine tunnel frame. The machine is operated in two distinct modes, namely, a right and left hand mode, and includes power steering means and additional power means to quickly change the machine from right to left hand operational mode to releasably lock it in either mode. In both operational modes, the machine's tracking wheels are maintained at acute angles to said tunnel axis. By initially attacking the deep layer of waste material along a boundary or margin thereof and following in the pathway which the machine clears for itself through the material, the wheels of the machine are enabled to run on solid ground at all times in spite of the great depth of the waste material layer and the absence of windrows. When moving on subsequent pathways through the material, the tracking wheels follow previously-cleared pathways through the material while simultaneously following in the new pathway being cleared by the machine. The material treatment takes place continuously and the worked material is discharged by the machine to the rear at an oblique angle into the preceding pathway to refill the same and maintain the continuity of the waste material layer.